Plastic composition comprising mineral powder, wood dust, and adhesive



Patented Jan. 16, 1951 PLASTIC COMPOSITION COMPRISING MIN- ERAL POWDER,WOOD DUST, AND ADHE- SIVE Raymond I. Billington and Ralph J. Nelson,Saugus, Mass.

No Drawing. Application March 16, 1945, Serial No. 583,166

This invention relates to a plastic composition adapted to be appliedfor example in the general manner of putty but adapted to adhere morefirmly and to attain a much greater permanent strength and havingfurther advantages. The composition is useful in many applications andits properties will be explained in connection with its use in patternmaking.

As is well known in pattern making and foundry practice, fillets areapplied at all reentrant angles of patterns. For instance, if a patternis of L-shaped cross section, the pattern can most easily be made byjoining two flat strips to make an L-shaped section and then making afillet in the interior corner of the L. Customarily such fillets aremade by applying putty to the corner or by securing in place in thecorner a strip of preformed wax having an outer facing of cloth. I Puttyis subject to the disadvantage among others of weakness and tendency tocrumble, and the further disadvantages of being slow to dry and notadhering to any metal parts of the pattern. In addition, putty does notprovide a suitable surface to receive a coating of lacquer. Preformedwax strips having cloth facings are subject to the disadvantage amongothers that when painted with lacquer the cloth shrinks and pulls awayfrom the body of the wax, no longer providing the desired roundedcontour at the corner of the pattern.

Our new plastic composition possesses marked advantages over the olderfillet materials. It is easily applied and adheres readily to wood ormetal. It can be compounded to harden to the hardness of wood, orgreater hardness, but its volume is not substantially affected by thehardening. When hard it may be sanded and smoothed to the same finish asthe wood of the pattern and it may be satisfactorily painted with thesame paint, for instance lacquer, with which the remainder of thepattern is painted. The sand used in the moulding operation does notstick to fillets made of the new composition, which has the advantage ofproducing smoother casting'sl The increased strength of the compositionis an advantage both in preventing breakage of the fillet during use inhandling of the pattern, and also in reinforcing the remainder of thepattern. The composition is moisture resisting and heat resisting.

Th solid constituents of the composition are mineral powder and wooddust (which is finely divided wood), preferably in the proportions offrom approximately 1 to approximately 2% 8 Claims. (Cl. 260-9) .2 partsof mineralpowder to 1 part thoroughly mixed.

The mineral constituent may comprise such powdered materials as Whiting,plaster of Paris, alum, magnesia, marble dust, zinc oxide and Frenchchalk. The mineral constituent preferably comprises a mixture containingwhiting and plaster of Paris in substantial proportions. The relativeproportions of whiting and plaster of Paris can be varied widely. Weprefer that the Whiting be-present in the ratio of approximately 1%parts to /{2 part ofplaster of Paris. Whiting appears to contribute tothe-sticking capacity of the plastic composition and plaster of Parisadds to the smoothness with which the plastic can be spread by atool.

As indicated above, there can be a substantial variation in proportionsof mineral powder and wood dust. One function of the mineral powderappears to be the prevention of shrinkage during hardening, and tosecure most nearly complete prevention of shrinkage it is best to haveat least 2 parts of mineral powder to 1 part of wood dust. However, themineral content can be reduced to 1 parts if a slight amount ofshrinking is permissible in use of the mixture, and for other uses themineral content may be reduced still further. It is preferred not toincrease the mineral powder to more than about 2% parts because as themineral powder content is raised higher than about 2 parts, thecomposition. loses some of its strength.

A typical preferred proportioning of the solid constituents is thus:

of wood dust,

Parts Whiting 1% Plaster of Paris Wood dust 1 hesives being preferred,Useful results can be secured for many purposes where strength but not ahigh degree of hardness is required by employing a binder consisting ofa viscous solution of rosin in ether or acetone. For greater hardness itis preferred to employ as the binder a solution containing a syntheticresin, plasticizer, and preferably also nitrocellulose, as Well asvolatile solvent. Suitable binders are available in the field of theheavy bodied lacquers known as brushing lacquers containing syntheticresins. Thus a preferred composition of the binder is 5 to 8%nitrocellulose (5 to 6 seconds) 3 to 6% plasticizers, such as dibutylphthalate, tricresyl phosphate, or heavy body castor oil '7 to 10%maleic resin, which is a resin used in lacquer manufacture, consistingof a combination of rosin and maleic acid with glycerine.

24 to 28% acetates, such as ethyl, butyl or amy-l 12 to 15% alcohols,such as ethyl or isopropyl 37 to 42% naphthas The addition of slightamounts of rosin to the above binder will tend to increase resiliency ofthe hardened composition.

While nitrocellulose is a useful and preferred ingredient in the binder,one should avoid any such predominance of the nitrocellulose as wouldcause a skin of nitrocellulose to form on the outer surface of a filletor the like before the underlying plastic com osition has suitablyhardened.

The liquid binder is added to the mixture of mineral powder and wooddust until the desired plastic consistency is secured and the productthen tightly sealed in a container to avoid premature hardening. Thussealed, the composition has good keeping qualities.

The plastic composition can readily be formed into a fillet by smoothingit into the corner of the pattern. No further ingredients need be addedat the time of use. No water need be applied to the composition torender it suitable for use,

which is a marked advantage in pattern-making because of the harmfuleffect 'of water upon wooden patterns. The composition forms an integral'part of the wood or metal pattern and exhibits no objectionableshrinkage. The fillet is strong and well able to withstand the roughhandling'whi'ch patterns may receive in the foundry. It may be finishedto a very smooth finish, and forms an excellent base for a lacquercoating.

The 'cornposition is also well adapted for use inrepairingor building upan article to which it is applied, for instance in building up a portionof 'a pattern to'a larger size, filling in depressions or pits in thesurface of a pattern or the like, or filling up a joint between twomembers. in all of which usesthe plastic composition strongly adhere tothe material to which it is applied, whether wood, metal, glass, brick,paper, a painted "surface or porcelain.

I Whil 'for ordinary use it is satisfactory to mix the wood-dustandmineral constituents and then apply the viscous binder to thismixture and seal the whole in a container, there are conditions whenitmay be advantageous to supply the wood dust separately from the mineraland binder ingradients. The mineral or minerals and the viscous bindermay be supplied in one container and the wood dust may be supplied in aseparate contai'ner or be furnished by the user of the composition.Inthis case it is advantageous'to mix with the wood dust a small amountof castor oil, for'e'xaniple 2 tablespoons of castor oil per poundofwooddus't, and allow these to stand well mixed for some time beforeuse so that the castor oil is "thoro'ughly absorbedby the wood dust.Then ashort time before use, the wood dust and other ingredients aremixed. This procedure still fur ther'reduces shrinkage, and resultsin'there being no more than an almost imperceptible amount of shrinkage,and is useful where relatively large bodies of the plastic are to beused, and it is required that the shrinkage of such large bodiesexceedingly small.

We claim:

1. A plastic composition consisting essentially of mineral powder, wooddust, an adhesive and volatile organic solvent for the adhesive, themajor constituents of the mineral powder being plaster of Paris andwhiting, the whiting being present in larger quantity than the plasterof Paris, the mineral powder and wood dust being in the proportion offrom 1%.; to approximately 2% parts of mineral powder to one part ofwood dust, and the composition being of putty-like consistency at normaltemperature and adapted to harden upon exposure to air.

2. A plastic composition consisting essentially of mineral powder, wooddust, an adhesive and volatile organic solvent for the adhesive, themineral powder including substantial proportions of both plaster ofParis and whiting, the quantity of the plaster of Paris and whitingbeing from 1 /2 to approximately 2 times the quantity of wood dust, andthe composition being of puttylike consistency at normal temperature andadapted to harden upon exposure to air.

3. A plastic composition consisting essentially of mineral powder, wooddust, an adhesive and volatile organic solvent for the adhesive, themajor constituents of the mineral powder being plaster of Paris andwhiting, the quantity of the plaster of Paris and whiting being from 1to approximately 2 ,4, times the quantity of wood dust, and-thecomposition being of putty-like consistency at normal temperature andadapted to harden upon exposure to air.

4. A plastic composition consisting substantially of mineral powder,wood dust, an adhesive and volatile organic solvent for the adhesive,the major constituent of the mineral powder 'being plaster of Paris andwhiting, the whiting being present in larger quantity than the plaster"of Paris, the mineral powder and wood dust being in the proportion offrom 1 to approximately 2 parts of mineral powder to one part of woo'ddust, and the composition being 'of putty-like consistency at normaltemperature and adapted to harden upon exposure to air.

5. A plastic composition consisting substantially of mineral powder,wood dust, an adhesive and volatile organic solvent for the adhesive,the mineral powder including substantial proportions of both plasterof'Paris and whiting, the quantity of the plaster of Paris and whitingbeing from 1 to approximately 2% times the quantity of wood dust, andthe composition being of puttylike consistency at normal temperature andadapted to harden upon exposure to air.

6.1-5. plastic composition consisting substantially of mineral powder,wood dust, an adhesive and volatile organic solvent for'the adhesive,themajor constituents of the mineral powder being plasterer Paris andwhiting, thequantity of the plaster of Paris and'whiting being from 1approximately 2%, times the quantity of wood dust, and the compositionbeing of putty-like consistency at normal temperature and adapted toharden upon exposure to air.

7. A foundry pattern which includes a builtup addition, said additionconsisting essentially of mineral powder and wood dust a'dhesivelybonded together and to the main body of'the pattern, the mineral powderand wood dust being 5 in the ratio of from 1 to approximately 2% partsof mineral powder to 1 part of wood dust, and the mineral powderincluding plaster of Paris to the extent of approximately one-half thequantity of wood dust.

8. A foundry pattern which includes a builtup addition, said additionconsisting essentially of mineral powder and wood dust adhesively bondedtogether and to the main body of the pattern, the mineral powder andwood dust being in the ratio of 1 /2 to approximately 2 parts of mineralpowder to 1 part of wood dust, and the mineral powder consistingsubstantially of whiting and plaster of Paris, the plaster of Parisbeing present to the extent of approximately one-half 15 the quantity ofwood dust, and the whiting being present in greater quantity than theplaster of Paris.

RAYMOND I. BILLINGTON. RALPH J. NELSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 764,849 Hubbard July 12, 19041,103,088 Schweitzer July 14, 1914 1,614,315 Pape Jan. 11, 19271,876,886 Ellis Sept. 13, 1932 2,175,096 Strauch Oct. 3, 1939 2,224,238Spitzli et a1 Dec. 10, 1940 2,316,099 Myers Apr. 6, 1943 FOREIGN PATENTSNumber Country Date 23,857 Great Britain of 1909 336,109 Germany Apr.21, 1921 OTHER REFERENCES Practical Pattern Making, by Barrows; 1906 TheNorman W. Henley Co., New York; pages 97 and 98.

Hackhs Chemical Dictionary, by Grant; Third Edition, 1944; The BlakistonCo., Philadelphia; page 696.

1. A PLASTIC COMPOSITION CONSISTING ESSENTIALLY OF MINERAL POWDER, WOODDUST, AN ADHESIVE AND VOLATILE ORGANIC SOLVENT FOR THE ADHESIVE, THELMAJOR CONSTITUENTS OF THE MINERAL POWDER BEING PLASTER OF PARIS ANDWHITING, THE WHITING BEING PRESENT IN LARGER QUANTITY THAN THE PLASTEROF PARIS, THE MINERAL POWDER AND WOOD DUST BEING IN THE PROPORTION OFFROM 1 1/2 TO APPROXIMATELY 2 1/4 PARTS OF MINERAL POWDER TO ONE PART OFWOOD DUST, AND THE COMPOSITION BEING OF PUTTY-LIKE CONSISTENCY AT NORMALTEMPERATURE AND ADAPTED TO HARDEN UPON EXPOSURE TO AIR.